Everyone's favorite line-building, time-wasting, procrastination aid video game turns 25 on Saturday. Yep, our friend Tetris is a quarter of a century old. Although technology has certainly advanced in 25 years, gameplay really hasn't changed much at all. And why should it? The beauty is in its simplicity. But that's not to say that marketers haven't tried to change the game "“ below, you'll find 10 variations on Tetris that have entered the market over the years. But you'll notice it's the original that still endures.

1. Hatris. In case the plain old blocks were a little too dull for you, Hatris provided you with the opportunity to stack different types of hats instead. Wizard hats, top hats, crowns"¦ whatever the variation was, you had to stack five alike hats in a row to get them to disappear.2. Faces. I had this one and I loved it. Each block that fell had an element of a face on it and you had to stack the pieces that went together to make the whole face go away and get points. Some of the faces were famous, so you should have had an easier time putting them together"¦ except a misprint in the booklet that went with the game messed up the images of two important people. "The pictures of George Washington Carver and Frederick Douglass (pp. 8 and 18) were inexplicably reversed. Please do not use their images as references for a U.S. History class," the insert explained.

3. Tetris Elements. Picture the design-a-disaster element from Sim City and there you have it. Five game variations offer five ways to destroy your hard work - "Stratosphere" had meteors, "Earthquake" featured tremors, "Tempest" switched between screens at inopportune times, "Ice" had falling icicles and "Fire" had intense heat that would melt rows.

4. Tetris Plus included a little professor guy that you needed to get to the bottom of the screen. The game starts with pre-placed tetrominoes, so it wasn't as easy as just starting the game and letting him drop. There's a decidedly evil element to this game "“ instead of just hitting the top and losing the game like usual, a loss in this game happened when the professor's skull came into contact with the metal spikes at the top of the playing field. Whoops.

5. Welltris. It was just like Tetris but with different dimensions. Imagine that you're looking down into a well "“ go figure, right? The tetrominoes fell down the sides of the well, giving the player all four sides to work with to get the pieces into position to eliminate lines. And "“ bonus "“ you also got to view "beautiful background scenes of modern Russian culture."6. Tetris: The GrandMaster was for serious players only. If regular Tetris was just too simple for you, even at level 50, then GrandMaster may have been up your alley. Once you reached a certain level (500, to be exact), the pieces were no longer airborne "“ they just appeared at the lowest level on the screen and the player only has a split second to move it before it was just locked into the place it appeared. The highest level was 999, at which point the player achieved the GrandMaster status.

7. Tetris Worlds included a backstory about a planet called Hadar 4, objects called Tetrions and little beings called Minos. To rescue the Minos from Hadar 4 as it has become uninhabitable, and to do so, you have to "“ well, play Tetris. Their story is a little more convoluted than that, but that's the drift. The fun part comes in with the variations, including "Sticky Tetris," "Fusion Tetris" and "Hot-Line" Tetris.

9. Tetris Party is the newest addition to the Tetris family and is available via WiiWare for the Wii. I had no idea this existed and now I'm pretty sure I have to have it. You can play in several different modes, even using the Balance Board in one of them, which sounds really hard. You can also play co-op "“ working together to clear lines "“ and Stage Racer, in which the player guides a single tetrimino through a narrow maze without touching any walls.

10. Tetris 1-D. This isn't an official Tetris game, but I kind of got a kick out of it. Check it out for yourself.

Has anyone played any of these? Or do you have fond memories of playing Tetris for days on end? Share in the comments! I can tell you that my cell phone version of Tetris definitely got me through boring lectures in college on multiple occasions.